This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The goal of this project is to determine the pharmacodynamic anti-thrombotic effects of anti-sense oligonucleotides for reducing the production of coagulation factor XI in baboons. Subcutaneous administration of anti-sense factor XI, twice weekly for 1 month, has now been shown to prolong clotting times and reduce thrombus propagation in a baboon arteriovenous shunt thrombosis model. This treatment strategy has the potential to produce effective yet safer antithrombotic therapy.